PBS could have confronted head-on the question of whether the radio show, which aired 75 years ago tomorrow night on CBS, really did provoke hysteria and mass panic in the United States. That’s the conventional wisdom, and it makes for a deliciously good yarn — that Americans back then were so skittish or doltish or unaccustomed to electronic media that they readily believed the story of the lethal Martian invasion of Earth, as described in The War of the Worlds broadcast.

But a growing body of scholarship — which the documentary utterly ignored — has impugned the conventional wisdom and has offered a compelling counter narrative: The War of the Worlds program sowed no widespread chaos and alarm. Instead, listeners in overwhelming numbers recognized the program for what it was: A clever radio show that aired in its scheduled Sunday time slot and featured the not-unfamiliar voice of the program’s 23-year-old star, Orson Welles.

Edward Jay Epstein has dismissed as a “fictoid” the notion that the radio program touched off mass hysteria. “The accounts of suicides, heart attacks, traffic collisions and flights all proved to be unfounded,” Epstein wrote, adding:

“The program itself of course was a fiction. So was the ‘Mass Hysteria,’ which became part of American folklore about the power of the media.”

Michael Socolow, a journalism historian at the University of Maine, said this about The War of the Worlds broadcast in a thoughtful commentary for the Chronicle of Higher Education five years ago:

“Nobody died of fright or was killed in the panic, nor could any suicides be traced to the broadcast. Hospital emergency-room visits did not spike, nor, surprisingly, did calls to the police outside of a select few jurisdictions. The streets were never flooded with a terrified citizenry.”

Socolow more recently has written a superb assessment of the broadcast, which was posted today at Slate.com. In it, he wrote:

“The supposed panic was so tiny as to be practically immeasurable on the night of the broadcast.”

Fifteen years ago, at the 60th anniversary of The War of the Worlds dramatization, Robert E. Bartholomew, an international expert on mass panic, pointed to a “growing consensus among sociologists that the extent of the panic” created by Welles’ program, “was greatly exaggerated.

“The irony here,” Bartholomew wrote, “is that for the better part of the past sixty years many people may have been misled by the media to believe that the panic was far more extensive and intense than it apparently was.”

The panic, to be sure, was overstated. Exaggerated. And has become the stuff of a tenacious media-driven myth.

As I wrote in my 2010 mythbusting book, Getting It Wrong, “the notion that TheWar of the Worlds program sent untold thousands of people into the streets in panic, is a media-driven myth that offers a deceptive message about the influence radio wielded over listeners in its early days and, more broadly, about the media’s potential to sow fright, panic, and alarm.”

I also discuss in Getting It Wrong a little-studied secondary phenomenon associated with The War of the Worlds broadcast, that “a false-alarm contagion took hold that night” in which well-intentioned people possessing little more than an incomplete understanding of Welles’ program set out on their own to warn others about a sudden and terrible threat.

These would-be Paul Reveres, I wrote, “burst into churches, theaters, taverns, and other public places, shouting that the country was being invaded or bombed, or that the end of the world was near.

“It had to have been a cruel and unnerving way of receiving word of a supposedly calamitous event — to be abruptly disturbed in familiar settings by a vague reports offered by people who themselves clearly were terror-stricken. … In more than a few cases, a contagion took hold: Many non-listeners became quite frightened, thus compounding for a short time the commotion and confusion stemming from The World of the Worlds program.”

PBS might well have examined that effect. It might have more seriously considered the broader counter-narrative that has taken shape about the radio dramatization.

PBS might have examined, in ways revealing to its audience, how media influences are not transmitted like a narcotic injected by hypodermic needle. News and entertainment media exert influences in ways that typically are far more subtle, nuanced, complex, and uneven.

But to believe The War of the Worlds radio program stirred chaos, mass panic, and widespread hysteria is effectively to embrace the hypodermic needle theory of media influence — a theory discredited long ago .

The age, class, wealth, education, political views, and life experiences of media audiences all are factors as to how media messages are absorbed and interpreted — if they are absorbed at all.

Socolow in his Chronicle article in 2008 noted the uneven and often-limited effects of media messages, writing:

“If we really know how to control people through the media, then why isn’t every advertising campaign a success? Why do advertisements sometimes backfire? If persuasive technique can be scientifically devised, then why do political campaigns pursue different strategies? Why does the candidate with the most media access sometimes lose?”

PBS — which says its mission is “to create content that educates, informs and inspires” — might have seized the opportunity of the 75th anniversary of The War of the Worlds broadcast to address such questions.

But, no: The documentary’s makers settled for a turgid program that was far less educational, informative, and inspiring than it could have been.

It’s a tempting claim of new media triumphalism that begs a one-word question: Where?

Where have social media taken down repressive governments?

Certainly not in Iran, where anti-regime protests sparked by a rigged presidential election in June 2009 gave rise to the misnomer, “Twitter Revolution.”

Twitter surely helped in organizing the demonstrations in Tehran. But social media proved no match for the Islamic government’s brutal crackdown that snuffed out the protests and shut down the threat to the regime.

Besides, Twitter became a channel for erroneous information — and disinformation — during the Iranian protests. Media critic Jack Shafer wrote at the time that Twitter was “more noise than signal in understanding the Iranian upheaval.”

So where else?

Egypt? A somewhat stronger case can be made there, that new media platforms contributed to the downfall nearly a year ago of Hosni Mubarak’s corrupt, 29-year authoritarian regime.

But even there, social media cannot be seen as decisive. They acted more as propellants in Egypt than as causal or precipitating agents.

In other words, the regime was mostly clueless about online countermeasures, how to turn social media to perverse use as instruments for identifying, spying on, and sidelining malcontents and regime foes.

Morozov wrote that “dictators learn fast and are perfectly capable of mastering the Internet” in countering populist threats to their regimes. He also noted that some authoritarian governments “have turned mostly to Western companies and consultants for advice about the technology of repression.”

A recent, searching study about social media and political upheaval across the Middle East notes:

“There can be no doubt that online activism is a significant phenomenon that has had a major impact on the Arab Spring.

“Yet, we would be wise not to exaggerate its influence.”

Mubarak’s fall, the study adds, wasn’t “the result of online activism alone. This would ignore the major roles played by those [in Egypt] who had likely not even heard of Facebook or Twitter.”

The study, written by Tim Eaton and posted online this month at New Diplomacy Platform, says social media helped mobilize opposition to Mubarak’s unpopular regime.

But Eaton adds that “events in Tunisia … appear to have been the game-changer. The success of Tunisian activists in ousting President [Zine el-Abidine] Ben Ali motivated many Egyptians to seek to replicate their feat.”

That phenomenon is known as a demonstration effect, in which tactics and events in one context serve as a model or inspiration elsewhere.

Mubarak’s regime did shut down the Internet in Egypt last year, from January 28 to February 1, in a bungled attempt to cut off the flow of online information to anti-regime activists. But the move backfired.

“It wasn’t the Internet that destroyed Mr. Mubarak,” Morozov wrote, ” it was Mr. Mubarak’s ignorance of the Internet that destroyed Mr. Mubarak.”

To assert, as Clinton did last night, that social media can take down repressive governments is to offer a simplistic message of media triumphalism, one thinly supported by empirical evidence.

It is, moreover, an explanation that shortchanges understanding of the complex mechanics of regime change.

And embracing simplistic explanations is an important way in which media-driven myths — those false, dubious, improbable stories about the news media that masquerade as factual — can take hold.

As I write in my latest book, Getting It Wrong, more than a few media-driven myths have emerged “from an impulse to offer easy answers to complex issues, to abridge and simplify topics that are thorny and intricate.”

Social media are not inherently democratic. Nor have they proved decisive in bringing down authoritarian regimes.

The Post offers a discerning summary of the book, noting that it“takes a critical look at 10 stories that were either total fabrications or blown way out of proportion and yet became part of our popular culture.”

It also says Getting It Wrongoffers “an exquisitely researched and lively look at an industry that too often shines the light on itself more than it does on events and public figures.”

And it notes, quite correctly:

“Much of the ‘wrong’ coverage through the years comes from the media’s self-congratulatory preening.”

The review points out that the sternest criticism in Getting It Wrongis reserved “for coverage, mainly by television, of the chaotic aftermath of Hurricane Katrina in New Orleans in 2005.

“Hyperactive reporters told tales of snipers roaming the streets, ‘hundreds’ of bodies stacked up in the Super Dome and babies being raped and murdered, none of which could be verified.

“Because the media are everywhere—and inspire much resentment—their influence is routinely exaggerated. The mistake is confusing visibility with power and the media are often complicit in the confusion. We [in the news media] embrace the mythology, because it flatters our self-importance.”

To bust media myths, I write in the book, “is to confront the reality that the news media are not the powerful agents they, and many others, assume them to be.

“It is exceedingly rare for any news report to trigger a powerful, immediate and decisive reaction akin to President Lyndon Johnson’s purported response to [Walter] Cronkite’s televised assessment about Vietnam: ‘If I’ve lost Cronkite ….’

“Researchers long ago dismissed the notion the news media can create such profound and immediate effects, as if absorbing media messages were akin to receiving potent drugs via a hypodermic needle,” I note, adding:

“Media power tends to be modest, nuanced, diffused, and situational.” And typically trumped by other, more powerful forces and factors.